I think you are over re-acting. When you do a job like your husband's, particularly when you work on a one to one basis with an employer, yes you can be come friends. My next door neighbours have a gardener and I have met him at social events they have held.
I have friend who has had the same domestic help for over 30 years. She is now treated as a member of the family. She goes to family events, everyone treats her as an old family friend. In these kind of situations these sort of entirely platonic friendships grow.
If your DH was playing away, would he have bought the mugs in your presence and told you who they were for?